A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick. Multiple tests for specific blood components (such as a glucose test or a cholesterol test) are often grouped together into one test panel called a blood panel or blood work.
Upper Air Troughs. When the height contours bend strongly to the south, (as in the diagram below), it is called a TROUGH. Strong troughs are typically preceded by stormy weather and colder air at the surface. Here is an example of a trough in an upper-level height field (red contours).
Air pressure. Air is light but because there is so much of it above us, it exerts a pressure on us. Air pressure is measured by a barometer. The units used are millibars. The greater the reading, the higher the pressure. A high-pressure system is called an anticyclone [anticyclone: High pressure systems, giving clear skies and gentle wind.] . Air falls in an anticyclone so no clouds are formed. In summer, high pressure usually results in clear skies, gentle breezes and fine weather.